[blatz]

Most programs allow both, actually your choice.  Only one functional at a time.

actually, with Beersmith 2, I believe it will show you the calcs for both.

Just sayin'

[dmtaylor]

Tinseth is the only formula that is reasonably accurate.  At least, up to about 90 IBUs, after which point it could calculate 5 billion IBUs but you just ain't getting it in real life.

[weithman5]

my caveat to this is how to estimate for homegrown hops. i always use the norm aau for the variety, but this could vary year to year. for the most part i stick with tinseth, usually do most of my own math but starting to use programs due to laziness. i rarely consider brewing something heavily hopped that tinseth would be grossly inaccurate,

[narvin]

IBU is also a measure of bitterness, not a measure of hoppiness like many people assume.  You can have the same amount of isomerized alpha acids in two different beers with a drastic difference in hop flavor and aroma based on the amount of beta acids and other compounds.

[dmtaylor]

With homegrown hops, of course, the initial estimate for alpha acid is always a swag.  It's best to brew a style where IBUs don't matter so much.  I always say, you should shoot for a pale ale -- then if it's too bitter, call it IPA, and if not bitter enough, then call it a blonde or amber ale.  After that initial batch, you can refine the alpha acid estimate on subsequent batches based on the taste of the first one or two, so that by the third and fourth batch, your refined estimate is literally within about 0.2 to 0.3 percent of the actual alpha acid, which to me seems close enough.  But we digress......

[morticaixavier]

I think to some extent what IBU has become in the commerical beer world (and to some extent in the homebrew world as well) is a short hand to express how much hops of what level of alpha acid content were used in the brew.

The OP mentioned 1000 IBUs at one point. I assume he is talking about the mikkeller product '1000 IBU' what I will say about that beer is that it is the MOST BITTER BEER i have ever tasted. There may be only 90 IBU there by lab standards and 85 ppm active compound but that beer tastes like what the name says.

Perhaps there is need for another notation aside from 'we used 12 lbs of 14% AA hops in this bottle of beer' because that is clunky. Perhaps we need something more like the scovile heat scale used for peppers. That is a subjective measure of how many squirts of sugar water it takes to calm the feeling of heat in the mouth after chewing a piece of a given pepper.

In the case of scovile there may be an actual relationship between the amount of capsaisin (sp?) in the pepper but it is still inherently a subjective measure as it depends on the subjects threshold for percieving the 'heat' of the pepper.

Similarly, while there may not be a direct relationship between the ppm of iso-alpha and perceived bitterness in a beer there is a very real (subjectivly) experience of much higher level of bitterness in some beers.

[denny]

Get your homegrown hops tested for $35.  They do beer testing, also.

http://hopunion.com/27_HopTesting.cfm?p5=open

[tygo]

Get your homegrown hops tested for $35.  They do beer testing, also.

http://hopunion.com/27_HopTesting.cfm?p5=open

That's a really cool service.  Thanks for posting the link.

[ketch32]

Awesome info - thank you all for great feedback and education on the subject.  Love how you can get the bittering levels actually verified, which if I was selling my beer and claiming outrageous levels, I could actually back it up.  As a consumer I wish that the claims on a bottle were true and somewhat telling of the product, you know from honest brewers.   I just saw this article that seemed to address this issue and my concern for the IBU standardization, if I say my beer has the highest IBU's of any beer, and thus, you should pay me $45 per bottle, am I telling you the truth, or just trying to get your money for all the hops and/or extract I bought, as well as the lost beer due to all the hop sediment?: http://mybeerbuzz.blogspot.com/2011/06/flying-monkey-claims-highest-ibu-beer.html.

There are alcohol levels stated on beer labels.  There are special ingredients, like ginger, stated on beer labels.  There are even stories about where the water comes from on beer labels.  Do you see any of those type of claims being misrepresented as much as IBU claims?  Education is the key, and again I thank you for helping educate me.

Cheers!

[hopfenundmalz]

The 2500 is in theory, not in practice.  They need to back that up with a lab analysis..  I think they wil not do that.   Emperor and no clothes comes to mind.

[a10t2]

The IBU is standardized. It's the absorbance of beer that's been mixed with a reagent, measured via a spectrophotometer at a particular wavelength. That's what an IBU is. You can try to correlate the results of the test to the amount of alpha acids added to the wort, but only if you understand the limitations of your correlation. As was said here, one major limitation to IBU estimation is the saturation limits of the iso-alpha acids. So anyone who claims an IBU level above 100 is almost certainly blindly reporting the result of a formula, without understanding its limitations. (Or reporting a value they know to be false.)


If you want to look up the procedures for the assay they're available from the ASBC.

There are alcohol levels stated on beer labels.

Almost all of which are also incorrect, being the result of formulas rather than measurements.

[Jimmy K]

Setting aside calculations vs practical limits, you're also confusing IBU, which is a chemical concentration measure, with bitterness, which is a flavor characteristic. IBU can predict bitterness, but the actual bitterness that you taste depends on other factors - maltiness and residual sugars will decrease perceived bitterness, high alcohol may also decease it, and hop flavor and aroma, while not affecting IBU's, often increase the perception of bitterness on your tongue.

Expecting IBU to be a one-stop measure is like being asked how fast your car is and answering 'red'.

[dmtaylor]

There are alcohol levels stated on beer labels.

Almost all of which are also incorrect, being the result of formulas rather than measurements.

Actually I think the physical properties of alcohol/water mixtures are pretty well known to the point that if you're off by 0.1% ABV, no one's going to fret about that.  And it's not solely based on formulae -- you can easily take OG and FG readings with a hydrometer to confirm theory.  With IBUs, though, not so simple.  Anybody have a photospectrometer just laying around? 

[morticaixavier]

There are alcohol levels stated on beer labels.

Almost all of which are also incorrect, being the result of formulas rather than measurements.

Actually I think the physical properties of alcohol/water mixtures are pretty well known to the point that if you're off by 0.1% ABV, no one's going to fret about that.  And it's not solely based on formulae -- you can easily take OG and FG readings with a hydrometer to confirm theory.  With IBUs, though, not so simple.  Anybody have a photospectrometer just laying around? 

OG less FG is a formula. and not a precise measurement of ABV. You've got other disolved solids, the differential between density of alchahol v water or water sugar.

[tschmidlin]

OG less FG is a formula. and not a precise measurement of ABV. You've got other disolved solids, the differential between density of alchahol v water or water sugar.

More importantly, the reported ABV is what they predict or actually got for a batch or two, then had printed on thousands and thousands of labels with no changes to the label even if the beer drifts or has batch to batch variation.  I'm sure what the mega brewers report is dead on, micros not so much.